Used a 10 stop nd filter on a lot of these shots. Some are HDR and some are not. Ones that are not I used my usual processing methods ie. Lightroom CC and a couple of pluggins. The nd filter enabled me to really milk the water, some like it some not. Problem with the filter is it really slows shutter speeds and if there is a wind and trees or any kind leaves in the frame they will blur.To each his own, on this set of shots I'm in the middle....leave me your thoughts if you care to...